, diane sawyer, joins us with the latest in on ongoing abc news series, hidden america. this one, from the streets of chicago. diane, the powerful report we're about to see really takes us inside what can only be described as a hidden american war zone. >> it is true, but we want to say at the outset, as we know, chicago is simply a great city, filled with wonderful people. but as we're going to show you, there are some areas, where small children really do live, as we said, in a kind of battle zone. so, listen to this number. at least 419 people were killed this year, across a dozen neighborhoods in chicago, and that is more than all the u.s. troops killed in afghanistan this year. the cause? rival gangs, creating anarchy. and, so, "nightline" and "world news" decided to try something different, something unprecedented. we gathered 38 members of rival gangs, past and present, from hispanics to their black rivals, to talk about the slaughter and how to make it stop. tonight, in america, tens of thousands of children are living in a war zone. one of them is a little boy named ralph. hey